v· special relativity, it refers to the Newtonian physics which preceded relativity, i.e. the branches of physics based on principles developed before the rise of relativity and quantum mechanics. When discussing general relativity, it refers to the result of modifying Newtonian physics to incorporate special relativity. When discussing quantum mechanics, it refers to non-quantum physics, including special relativity, and general relativity. In other words, it is the physics preceding the physics of interest in one's discussion.
In the context of general and special relativity, "classical theory" refers to classical mechanics, and other theories which obey Galilean relativity. Light and other electromagnetic pheneomena cannot be correctly modeled in such a theory. Traditionally, light was reconciled with classical mechanics by assuming the existence of a "stationary" medium through which light propagated, the luminiferous aether.
The existence of these two distinct meanings of the term can lead to confusion: special relativity is a "classical theory" in the first sense, but its predictions are more accurate than "classical theory" in the second sense.
In other contexts, "classical theory" will have other meanings—if a current accepted theory is considered to be "modern", and its introduction represented a major paradigm shift, then previous theory (or new theories based on the older paradigm) will often be referred to as "classical".
Among the branches of theory included in classical physics are:
A physical system on the classical level is a physical system in which the laws of classical physics are valid. There are no restrictions on the application of classical principles, but, practically, the scale of classical physics is the level of isolated atoms and molecules on upwards, including the macroscopic and astronomical realm. Inside the atom and among atoms in a molecule, the laws of classical physics break down and generally do not provide a correct description.
Moreover, the classical theory of electromagnetic radiation is somewhat limited in its ability to provide correct descriptions, since quantum effects are observable in more everyday circumstances than quantum effects of matter. Unlike quantum physics, classical physics is generally characterized by the principle of complete determinism (although the Many-worlds interpretation of quantum mechanics is in a sense deterministic).
Mathematically, classical physics equations are ones in which Planck's constant does not appear. According to the correspondence principle and Ehrenfest's theorem as a system becomes larger or more massive (action >> Planck's constant) the classical dynamics tends to emerge, with some exceptions, such as superfluidity. This is why we can usually ignore quantum mechanics when dealing with everyday objects; instead the classical description will suffice. However, one of the most vigorous on-going fields of research in physics is classical-quantum correspondence. This field of research is concerned with the discovery of how the laws of quantum physics give rise to classical physics in the limit of the large scales of the classical level.
classical physics — klasikinė fizika statusas T sritis fizika atitikmenys: angl. classical physics vok. klassische Physik, f rus. классическая физика, f pranc. physique classique, f … Fizikos terminų žodynas
classical physics — noun a) all aspects of physics developed before the rise of quantum mechanics b) The division of physics that encompasses the three major areas of mechanics, electrodynamics, and thermodynamics, all of which were developed prior to the… … Wiktionary
Philosophical interpretation of classical physics — Classical Newtonian physics has, formally, been replaced by quantum mechanics on the small scale and relativity on the large scale. Because most humans continue to think in terms of the kind of events we perceive in the human scale of daily life … Wikipedia
Glossary of classical physics — This article is a glossary of classical physics. It is some of the most common terms in classical physics and how they are used.AlphanumericTOC align=center nobreak= numbers= externallinks= references= top=| A * Acceleration the rate of change of … Wikipedia
Physics — (Greek: physis φύσις), in everyday terms, is the science of matter [R. P. Feynman, R. B. Leighton, M. Sands (1963), The Feynman Lectures on Physics , ISBN 0 201 02116 1 Hard cover. p.1 1 Feynman begins with the atomic hypothesis.] and its motion … Wikipedia
physics — [fiz′iks] n. [transl. of L physica, physics < Gr (ta) physika (lit., natural things), name given to the physical treatises of ARISTOTLE: see PHYSIC] 1. Obs. natural philosophy 2. a) the science dealing with the properties, changes,… … English World dictionary
Classical mechanics — This article is about the physics sub field. For the book written by Herbert Goldstein and others, see Classical Mechanics (book). Classical mechanics … Wikipedia
physics — /fiz iks/, n. (used with a sing. v.) the science that deals with matter, energy, motion, and force. [1580 90; see PHYSIC, ICS] * * * I Science that deals with the structure of matter and the interactions between the fundamental constituents of… … Universalium
Classical — The word classical has several meanings. In general, these meanings refer to some past time, works of that era or later works influenced by that time. Classical things are often seen as ordered and part of high culture or a golden age, and… … Wikipedia